27. It has been found by experiment that all perfect gases will expand 1/460 of their volume when heated from zero to 1° above. It is inferred, therefore, that the ultimate limit of contraction would be found at 4G0° below zero of the Fahrenheit scale, and that at this point all motion of the molecules ceases. This point is called absolute zero, and temperatures measured from this point are called absolute temperatures. The temperature which is indicated by the thermometer may be converted into absolute temperature by adding it to 460°. Thus, a temperature of 85° by the thermometer corresponds to the absolute temperature of 85+460 = 545°.

Hereafter, where temperatures are mentioned, t will denote the ordinary temperature indicated by the thermometer, and T, the absolute temperature; hence, on the Fahrenheit scale, T = 460° + t.

## Example

What are the absolute temperatures corresponding to the ordinary temperatures 212°, 32°, and -39.2° Fahrenheit?

## Solution

 T = 460° + 212° = 672°. Ans. T = 460° + 32° = 492°. Ans. T = 460° - 39.2° = 420.8°. Ans.

## Example

If the absolute temperature is 682°, what is the temperature as shown by a Fahrenheit thermometer?

## Solution

t = T-4600 = 682°-460° = 222°. Ans.